Surgical intervention of damaged or compromised bone sites has proven highly beneficial for patients, including, for example, patients with back pain associated with vertebral damage. The vertebral damage may be due to injury and/or a degenerative condition such as, for example, aging and/or osteoporosis.
Bones of the human skeletal system include mineralized tissue that may be generally categorized into two morphological groups: “cortical” bone and “cancellous” bone. Outer walls of all bones are composed of cortical bone, which is a dense, compact bone structure characterized by a microscopic porosity. Cancellous or “trabecular” bone forms the interior structure of bones. Cancellous bone is composed of a lattice of interconnected slender rods and plates known by the term “trabeculae”.
During certain bone-related procedures, cancellous bone is supplemented by an injection of a palliative (or curative) material employed to stabilize the trabeculae. For example, superior and inferior vertebrae in the spine may be beneficially stabilized by the injection of an appropriate, curable material (e.g., PMMA or other bone cement or bone curable material). In other procedures, percutaneous injection of stabilization material into vertebral compression factors, by, for example, transpedicular or parapedicular approaches, has proven beneficial in relieving pain and stabilizing damaged bone sites. Such techniques are commonly referred to as vertebroplasty.
A conventional vertebroplasty technique for delivering the bone stabilizing material entails placing a cannula with an internal trocar into the targeted delivery site. The cannula and trocar are used in conjunction to pierce the cutaneous layers of a patient above the hard tissue to be supplemented, then to penetrate the hard cortical bone of the vertebra, and finally to traverse into the softer, cancellous bone underlying the cortical bone. After the assembly is positioned in the cancellous bone, the trocar may be removed, leaving the cannula in the appropriate position for delivery of curable material that will reinforce and solidify the target site.
In some instances, an effectiveness of the procedure may be enhanced by forming a cavity or void within the cancellous bone, and then depositing the curable material in the cavity. For example, a balloon or other expandable device may be initially deployed and then expanded in a particular vertebroplasty procedure sometimes referred to as kyphoplasty. This action, in turn, compresses cancellous bone and other tissue to form a cavity, and may also cause a “height” of the bone to increase. As a point of reference, vertebroplasty is a common treatment for a fractured vertebral body, and the height of a fractured vertebral body is oftentimes significantly less than a native or natural height that existed before vertebral degeneration. It has been postulated that the height of a fractured vertebral body may be restored or elevated to a near-normal state when subjected to internal expansion via a balloon or other expandable member. The mechanics of height restoration in conjunction with vertebroplasty stabilization is currently unclear at best. For example, certain techniques may employ a bipedicular approach in which two balloons are inserted into the vertebral body and inflated, resulting in an increase in height (and the cavity or cavities described above).
There exists a need in the medical device field for improved systems and methods for restoring the height of, and stabilizing, a fractured vertebral body or other bone structure. In particular, it would be desirable to provide apparatus and methods to symmetrically provide bone augmentation that stabilizes a bone structure such as a vertebra, and that may also provide some height-restoration of said bone structure.
It may be desirable to provide a system and method that provides advantages with regard to reduced complexity and reduced procedure time while maintaining advantages of dual-balloon kyphoplasty and perhaps offering superior bone-centralization and symmetry of curable material placement.